WO2006028124A1

WO2006028124A1 - Roller screw

Info

Publication number: WO2006028124A1
Application number: PCT/JP2005/016406
Authority: WO
Inventors: Akihiro Teramachi; Hidekazu Michioka; Hiroshi Niwa; Akimasa Yoshida
Original assignee: Thk Co., Ltd.
Priority date: 2004-09-08
Filing date: 2005-09-07
Publication date: 2006-03-16
Also published as: KR20070099529A; US8272289B2; EP1801458A1; US20080245170A1; JPWO2006028124A1; JP4712717B2; EP1801458A4; CN101036004B; KR101232398B1; CN101036004A; EP1801458B1

Abstract

A roller screw having a structure suitable for circulating rollers. The roller screw has a screw shaft (5) in the outer peripheral surface of which a spiral roller rolling groove (5a) is formed, a nut (6) in the inner peripheral surface of which a spiral roller rolling groove (6a) facing the roller rolling groove (5a) of the screw shaft (5) is formed, and rollers (7) arranged in a load roller rolling path (9) between the roller rolling groove (5a) of the screw shaft (5) and the roller rolling groove (6a) of the nut (6). Inside the nut (6) is provided a roller return path (11) extended straight in parallel to the axis of the nut (6). Direction change-over path forming members (13) are attached to both end surfaces in the axial direction of the nut (6), and direction change-over path forming members (13) form direction change-over paths (10) that connect the load roller rolling path (9) and the roller return path (11). The roller return path (11) is twisted so that the attitude of the rollers (7) is rotated while they move in the roller return path (11).

Description

Specification

Roller screw

Technical field

[0001] The present invention relates to a roller screw having a roller interposed between a screw shaft and a nut so as to allow rolling motion.

Background art

[0002] A ball screw in which a ball is interposed between a screw shaft and a nut so as to allow rolling motion can reduce a friction coefficient when the screw shaft is rotated with respect to a nut, compared with a screw that is in sliding contact. It has been put to practical use in machine tool positioning mechanisms, feed mechanisms, and automobile steering gears.

[0003] In recent years, in order to increase the allowable load, a roller screw using a roller instead of a ball as a rolling element has been devised as disclosed in Patent Document 1. This roller screw uses a return pipe to circulate the roller. The roller rolling up the roller rolling groove of the screw shaft is lifted by the return pipe, passes through the return pipe, returns to the original position, and circulates indefinitely. This return pipe is formed in a substantially gate shape as a whole, and consists of a central portion and both end portions bent with respect to the central portion. The connecting portion between the central portion and both end portions is formed in an arc shape in order to smoothly circulate the roller.

Patent Document 1: Japanese Patent Laid-Open No. 2001-241527

Disclosure of the invention

Problems to be solved by the invention

As shown in FIG. 19, the rollers la and lb are accommodated between the roller rolling groove 2 a of the screw shaft 2 and the roller rolling groove 3 a of the nut 3. The roller la on the roller rolling groove 2a and the roller lb on the adjacent roller rolling groove 2a must be at least as long as the diagonal length of the rollers la and lb. There is a tendency for the lead L of the roller rolling grooves 2a and 3a to increase. If the roller diameter is increased or the number of strips is increased to increase the allowable load, the lead L becomes even larger.

[0005] As for the shape of the return nose, in order to smoothly circulate the roller, It was necessary to increase the radius of curvature of the arc at the joint between the center and both ends of the eve compared to the ball screw so that the roller would not clog the arc.

[0006] When attaching the return nove to the nut, check the groove on the side of the nut and fit the return pipe into the groove. If the lead force increases and the radius of the arc of the return nose increases, the roller rolling groove of the nut escapes (without the return pipe mounting groove interfering with the roller rolling groove). It was difficult to design a groove in which a return nove was attached to the nut.

[0007] Unlike the ball, the roller has a rectangular side shape, and the load roller rolling path between the screw shaft and the nut also has a rectangular cross-sectional shape. When rolling up the roller from the loaded roller rolling path and returning the roller to the loaded roller rolling path, the posture of the roller must be matched to the shape of the loaded roller rolling path to smoothly circulate the roller. There is.

[0008] Therefore, an object of the present invention is to solve these problems and to provide a screw screw screw having a structure suitable for circulating a roller.

Means for solving the problem

Hereinafter, the present invention will be described. In order to facilitate understanding of the present invention, reference numerals on the attached drawings are appended in parentheses, but the present invention is not limited to the illustrated form.

[0010] In order to solve the above problems, the invention of claim 1 includes a screw shaft (5) in which a spiral roller rolling groove (5a) is formed on the outer peripheral surface, and the screw shaft ( 5) a nut (6) formed with a spiral roller rolling groove (6a) facing the roller rolling groove (5a), and the roller rolling groove (5a) of the screw shaft (5). And a plurality of rollers (7) arranged in a loaded roller rolling path (9) between the nut and the roller rolling groove (6a) of the nut (6). A roller return passage (11) extending linearly in parallel with the axis of the nut (6) is provided in the inner side of the nut (6), and the load roller is provided at both end surfaces in the axial direction of the nut (6). A direction change path constituting member (13) is formed, in which a direction change path (10) connecting the rolling path (9) and the roller return path (11) is formed.

[0011] The invention of claim 2 is the roller screw according to claim 1, wherein the posture of the roller (7) rotates while the roller (7) moves in the roller return passage (11). The mouth The roller return passage (11) is twisted.

[0012] The invention of claim 3 is the roller screw according to claim 2, wherein the center line of the pair of direction change paths (10) provided on both end faces of the nut (6) is the screw shaft (5) The roller return passage (11) intersects the roller (7) by rotating the posture of the roller (7) by the predetermined opening angle (a). Features.

[0013] The invention of claim 4 is the roller screw according to claim 2 or 3, wherein the nut (6) is formed with a through hole (17) extending in an axial direction of the nut (6), A roller return path constituting member (12) in which the roller return path (11) is formed is inserted into the through hole (17).

[0014] The invention of claim 5 is the roller screw according to any one of claims 2 to 4, wherein the roller rolling groove (5a) of the screw shaft (5) is formed in a V-shaped cross section, and the nut The roller rolling groove (6a) of (6) is also formed to have a V-shaped cross section, and the loaded roller rolling path (9) has an adjacent roller ( The plurality of rollers are cross-arranged so that the axes of 7) are orthogonal to each other.

[0015] The invention of claim 6 is the roller screw according to any one of claims 1 to 5, wherein the direction change path constituting member (13) is attached to the direction change path constituting member (13). A thin-walled portion (23) that protrudes toward the nut from the end face of (6) and is curved in accordance with the shape of the direction changing path (10) is formed, and the direction changing path constituting member (13) An escape groove (19) having a shape matched to the thin portion (23) of the direction change path component (13) is formed on an end surface of the nut (6) to be attached. The invention's effect

[0016] According to the invention of claim 1, even if the lead is large, the roller return passage and the direction change passage can be designed without interfering with the roller rolling groove of the nut.

[0017] According to the invention of claim 2, the load roller rolling path force also lifts the roller, and when returning the roller to the load roller rolling path, the posture of the side rectangular roller is changed to a load port having a rectangular cross section. It is possible to match the shape of the la rolling road. In addition, if the orientation of the roller is rotated on the direction change path, the roller may be clogged. However, since the roller is rotated in the linear roller return path, there is no possibility of clogging the roller. [0018] If the posture of the roller is rotated as in claim 3, the load is applied from one direction of the screw shaft axis and the roller does not reverse! Return to the loaded roller rolling path (with the unidirectional force loaded).

[0019] According to the invention of claim 4, since the roller return passage constituting member extending linearly is separate from the nut, it is easy to manufacture a twisted direction change path.

[0020] The present invention is suitably used for a roller screw that is cross-arranged as described in claim 5.

[0021] According to the invention of claim 6, it is possible to prevent the direction change path constituting member from interfering with the roller rolling groove of the nut.

Brief Description of Drawings

FIG. 1 is a perspective view of a roller screw according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view of main parts of the roller screw.

[Fig. 3] Side view of a roller screw combining all components.

[Fig. 4] IV-IV arrow view of Fig. 3.

FIG. 5 is a side view showing a screw shaft.

FIG. 6 is a view showing a cross-sectional shape perpendicular to the groove of the roller rolling groove of the screw shaft.

FIG. 7 is a detailed view of the nut 6 ((A) shows a front view of the nut, (B) shows a cross-sectional view along the axial direction, and (C) shows a back view).

[FIG. 8] A detailed view of the mounting seat of the direction change path component ((B) is a cross-sectional view along line BB in (A)).

FIG. 9 is a view showing a cross-sectional shape of the nut roller rolling groove perpendicular to the groove.

[Fig. 10] Diagrams showing the path of rollers circulating in an infinite circuit ((A) shows the state seen from the axial direction of the screw shaft, and (B) shows the state seen from the side of the screw shaft).

FIG. 11 is a diagram showing a positional relationship between a pair of direction change path constituent members ((A) shows a state viewed from the axial direction of the nut, and (B) is a sectional view taken along the axial line of the nut).

FIG. 12 is a view showing the inner peripheral side of the direction change path constituting member ((A) shows a front view and (B) shows a side view).

FIG. 13 is a view showing the inner peripheral side of the direction change path constituting member ((A) shows a side view, (B) shows a back view). FIG. 14 is a view showing the outer peripheral side of the direction change path constituting member ((A) shows a front view and (B) shows a side view).

FIG. 15 is a view showing the outer peripheral side of the direction change path constituting member ((A) shows a side view and (B) shows a front view).

FIG. 16 is a cross-sectional view of a roller return path constituent member.

FIG. 17 is a view showing rotation of a posture of a roller moving in a roller return path.

[Figure 18] Detailed view of retainer.

FIG. 19 is a view showing a roller accommodated in a load rolling path.

Explanation of symbols

[0023] 5 ... Screw shaft

5a ... Roller rolling groove

6 ... Nut

6a Roller rolling groove

7 ... Laura

9… Loaded roller rolling path

10 ... turn around

11 · · · Roller return passage

12 ·· 'Roller return passage component

13 · · · Direction change path components

13a ... Inner peripheral side of direction change path component

13b ... The outer peripheral side of the direction change path component

17 ... through hole

19 ...

23 ... Thin part

α ... Opening angle

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 shows a perspective view of a roller screw according to an embodiment of the present invention. The roller screw consists of a screw shaft 5 having a spiral roller rolling groove 5a formed on the outer peripheral surface and a roller rolling groove formed on the inner peripheral surface. And a nut 6 formed with a spiral roller rolling groove 6a opposite to 5a. Between the roller rolling groove 5a of the screw shaft 5 and the roller rolling groove 6a of the nut 6, a plurality of rollers 7 are cross-arranged so that the axes of the adjacent rollers 7 are orthogonal to each other. A retainer 8 is interposed between the rollers 7 to prevent the rollers 7 from contacting each other.

[0025] When the nut 6 is rotated relative to the screw shaft 5, the plurality of rollers 7 move while rolling on the loaded roller rolling path 9 between the roller rolling groove 5a and the roller rolling groove 6a. . Roller Rolled up to one end of the rolling roller 9 is rolled up in the direction changing path 10 and returned to the original position via the roller return path 11 formed in the nut 6.

FIG. 2 is an exploded perspective view of main parts of the roller screw. A roller return path component 12 is inserted into the nut 6. The roller return passage constituting member 12 is formed in a pipe shape, and a roller return passage 11 for moving the roller 7 in the axial direction of the screw shaft 5 is formed therein.

[0027] Direction change path constituting members 13 are attached to both end faces of the nut 6 in the axial direction. An arcuate direction change path 10 that connects the loaded roller rolling path 9 and the roller return path 11 is formed in the direction change path constituting member 13. The direction change path component 13 scoops up the roller 7 rolling on the roller rolling groove 5a of the screw shaft 5, passes the direction change path 10 and then guides it to the roller return path 11. The direction change path component 13 is divided into two parts, an inner peripheral side 13a and an outer peripheral side 13b. The flanges on the inner peripheral side 13a and the outer peripheral side 13b of the direction change path constituting member 13 are coupled to the end face of the nut 6 by fastening means such as bolts.

[0028] Fig. 3 shows a side view of the roller screw in which all parts are combined, and Fig. 4 shows a view taken along line IV-IV in Fig. 3. In order to remove foreign matter and prevent the lubricant from leaking from the inside of the nut 6 on both end faces in the axial direction of the nut 6 in which the roller return path constituting member 12 and the direction changing path constituting member 13 are incorporated. For this purpose, a labyrinth seal 14 is installed. Then, the cap 15 is attached so as to cover the entire end face of the nut 6 to which the labyrinth seal 14 is attached.

FIG. 5 shows the screw shaft 5. A spiral roller rolling groove 5 a having a predetermined lead is formed on the outer periphery of the screw shaft 5. In this embodiment, the number of roller rolling grooves 5a is set to four in order to increase the allowable load and shorten the overall length of the nut 6. Of course, roller rolling groove 5 The number of items a can be set variously, such as one item, two items, and three items.

FIG. 6 shows the cross-sectional shape of the roller rolling groove 5a of the screw shaft 5 perpendicular to the groove. The cross section of the roller rolling groove 5a is V-shaped and its opening angle is set to 90 degrees. At the bottom of the roller rolling groove 5a, an arc portion 5b for grinding relief is formed so that a 90 ° intersection can also be ground.

FIG. 7 shows a detailed view of the nut 6. 7A shows a front view of the nut 6, FIG. 7B shows a cross-sectional view along the axial direction, and FIG. 7C shows a back view of the nut 6. On the inner peripheral surface of the nut 6, a spiral roller rolling groove 6 a that faces the roller rolling groove 5 a of the screw shaft 5 is formed. Further, the nut 6 is formed with a through hole 17 extending in the axial direction of the nut 6. The through hole 17 has a central portion 17a with a small diameter, and both end portions 17b on both sides of the central portion are formed with a slightly larger diameter than the central portion 17a. The roller return path constituting member 12 is inserted into the central portion 17a of the through hole 17, and the direction changing path constituting member 13 is inserted into both end portions 17b. A mounting seat 18 for attaching the direction change path constituting member 13 to the nut is formed on the end face in the axial direction of the nut 6, and the direction changing path constituting member 13 is attached to the mounting seat 18. The roller return path constituting member 12 and the direction changing path constituting member 13 are provided in a number equal to the number of the roller rolling grooves 6a (four in this embodiment), and the rollers 7 for rolling the four roller rolling grooves 6a are provided. Circulate.

FIG. 8 is a detailed view of the mounting seat 18 of the direction change path constituting member 13. The mounting seat 18 is formed with an arc-shaped escape groove 19 having a shape matched to a thin portion of a direction change path constituting member 13 described later. In a normal end cap type ball screw, the end face of the nut is flat and no relief groove is formed. Then, attach the members that make up the direction change path to the flat part. In the case of a roller screw, in order to circulate the roller 7 smoothly, the radius of curvature of the direction change path 10 is increased, and the direction change path component 13 is likely to interfere with the single roller rolling groove 6a of the nut 6. . By forming the relief groove 19 that matches the shape of the direction change path constituting member 13 on the end face of the nut 6, it is possible to prevent the direction change path constituting member 13 from interfering with the roller rolling groove 6a.

FIG. 9 shows a cross-sectional shape of the roller rolling groove 6a of the nut 6 perpendicular to the groove. The roller rolling groove 6a has a V-shaped cross section and an opening angle of 90 degrees. At the bottom of the roller rolling groove 6a, a circular arc portion 6b for grinding relief is formed so that a 90 ° intersection can be ground.

The roller 7 interposed between the screw shaft 5 and the nut 6 will be described. Roller rolling path The roller 7 that rolls 9 has a cylindrical shape, and its diameter and height are substantially equal. To be precise, the diameter of roller 7 is slightly larger than the roller height. For this reason, the shape of the roller 7 seen from the side is close to a square. In a ball screw, the ball carries a load in one direction of the axial direction of the screw shaft and in the opposite direction. On the other hand, since the roller 7 is compressed between the wall surface of the roller rolling groove 5a and the wall surface of the roller rolling groove 6a of the nut 6 facing the wall surface, the roller 7 applies a load. Only one load in the axial direction of the screw shaft 5 can be applied. By arranging the rollers 7 in a cross arrangement, it is possible to apply loads in one direction (1) and the other direction (2) in the axial direction of the screw shaft 5 (see FIG. 3).

[0035] The diameter D of the roller 7 has a so-called oversize larger than the distance between the wall surface of the roller rolling groove 5a of the screw shaft 5 and the wall surface of the roller rolling groove 6a of the nut 6 facing the wall surface. Things are used. For this reason, the roller is elastically deformed in the loaded roller rolling path 9, and a load corresponding to the elastic deformation exists in the nut 6 as a preload. Since the rollers 7 are cross-arranged in the load roller rolling path 9, the load applied from the rollers 7 to the nut 6 acts in a direction in which the adjacent rollers 7 repel each other.

FIG. 10 shows the trajectory of the rollers that circulate through the spiral load roller rolling path 9, the arc-shaped direction changing path 10, and the linear roller return path 11. Fig. (A) shows the roller trajectory (as viewed from the axial direction of the screw shaft) moving on the loaded roller rolling path 9, and Fig. (B) shows the roller trajectory circulating through the entire infinite circuit (screw (Viewed from the side of the shaft). The roller trajectory in the loaded roller rolling path 9 is spiral with a radius RCDZ2. The trajectory of the roller in the roller return passage 11 is a straight line parallel to the axis 5c of the screw shaft 5. The roller trajectory on the turning path 10 is an arc with a radius of curvature R. At the joint between the loaded roller rolling path 9, the direction changing path 10, and the roller return path 11, the tangential direction of the roller track is continuous. This smoothes these connections.

FIG. 11 shows the positional relationship between the direction change path constituting member 13 attached to one end face of the nut 6 and the direction change path constituting member 13 attached to the other end face. As described above, the center line of the roller return passage 11 extends parallel to the axis 5c of the screw shaft 5. The center line of the direction change path 10 extends in the tangential direction of the center line of the load port roller rolling path 9 when viewed from the axial direction of the screw shaft 5 as shown in FIG. And the center of the front turning path 10 The line and the center line of the rearward direction change path 10 intersect at a predetermined opening angle α. As will be described in detail later, the roller return passage 11 rotates the posture of the roller 7 moving in the passage by an angle α equal to the opening angle. The opening angle tends to increase as the radius of curvature of the turning path 10 increases. In this embodiment, the radius of curvature of the direction change path 10 is set to about 5 times the diameter D of the roller 7, for example, and the opening angle is set to 90 degrees to 100 degrees, for example.

[0038] By the way, with a return pipe type roller screw, the roller is lifted from the intersection P1 of the loaded roller rolling path 9 and the horizontal line 20 in the figure (Α) and returned to the intersection Ρ2 on the opposite side. The number becomes 2.5, 3, 5, 4, 5, etc., and the fraction becomes 0.5. On the other hand, in the roller screw of this embodiment, the opening angle α of the direction change path is 90 to: LOO degrees, and the Ρ3 point force is also increased and returned to Ρ4 point, so that the number of rolls of the roller is 2.7, 3. 7, 4. 7 turns, etc., and the fraction is 0.7. Compared with the return pipe type roller screw, the roller is evenly accommodated in the circumferential direction of the load roller rolling path 9, so the load balance of the roller screw is improved.

12 and 13 show the inner peripheral side 13a of the direction change path constituting member. The inner peripheral side 13a of this direction change path constituting member has a main body portion 21 in which a direction change path having a radius of curvature R is formed, and a flange portion 22 attached to the end face of the nut 6. At one end of the main body 21, a lifting portion 21 a that enters the loaded roller rolling path 9 and scoops up the roller 7 is formed. The other end of the main body 21 is fitted into the roller return path component 12. The lifting portion 21a on the inner peripheral side 13a cooperates with the lifting portion on the outer peripheral side 13b to lift the roller 7 that rolls on the spiral load roller rolling path 9 in the tangential direction. Immediately after scooping up the direction change path 10, the direction of the roller 7 is changed, and the roller is moved along the arc-shaped direction change path 10.

[0040] On the inner peripheral side 13a of the direction changing path member, it protrudes to the nut side from the end face of the nut 6 to which the direction changing path constituting member 13 is attached, and is bent in a curved shape according to the shape of the direction changing path 10 The thin portion 23 to be formed is formed. The cross-sectional shape of the thin portion 23 is formed in a V shape. This thin portion 23 is fitted into a relief groove 19 (see FIG. 8) formed on the end face of the nut 6.

14 and 15 show the outer peripheral side 13b of the direction change path constituting member. The outer peripheral side 13b of the direction change path constituting member has a main body part 25 in which the direction change path 10 having a radius of curvature R is formed, and a flange part 26 attached to the end face of the nut 6. At one end of the main body 25, there is formed a lifting portion 25a which enters the load roller-roller rolling path 9 and scoops up the roller. Main unit 25 The other end of the roller is fitted into the roller return path constituting member 12. The outer circumferential side raising portion 25a cooperates with the inner circumferential side raising portion 21a to raise the roller 7 rolling on the spiral loaded roller rolling path 9 in the tangential direction. Immediately after scooping up the direction change path 10, the direction of the roller 7 is changed, and the roller is moved along the arc-shaped direction change path 10. Further, on the outer peripheral side 13b of the direction changing path constituting member, a protruding portion 27 is formed in accordance with the shape of the roller rolling groove 5a of the screw shaft 5, thereby ensuring the strength of the lifting portion 25a. The direction change path component 13 may be made of metal or resin.

FIG. 16 shows a cross-sectional view of the roller return path component 12. While the roller passes through the roller return passage 11, the roller return passage 11 is twisted so that the posture of the roller rotates. The roller rotates around the center line 12 a while moving along the center line 12 a of the roller return passage 11. Here, the moving distance of the roller 7 and the rotation angle of the roller 7 are proportional. In this example, the roller 7 rotates 90 degrees + 2 β degrees (the opening angle of the pair of direction change paths as viewed from the axial direction of the screw shaft) until the one end force of the roller return passage 11 reaches the other end. The roller return path component 12 is divided into two along the center line. The roller return path constituting member 12 may be made of metal or resin.

FIG. 17 shows the rotation of the posture of the roller 7 moving in the roller return path 11. From FIG. 17, it can be seen that as the roller return passage 11 is moved, the position of A1 of the roller 7 moves to the left diagonally upward force and diagonally to the left, and the posture of the roller rotates about 90 degrees.

[0044] By rotating the posture of the roller 7 in the roller return path 11, the roller 7 is scooped up from the loaded roller rolling path 9 and when the roller 7 is returned to the loaded roller rolling path 9, the side rectangular roller The posture of 7 can be matched with the shape of the load roller rolling path having a rectangular cross section. Also, if the orientation of the roller 7 is rotated in the arc-shaped direction change path 10, the roller may be clogged, but the roller may be rotated in the linear roller return path 11, so the roller may be clogged. Nah ...

[0045] In addition, by rotating the posture of the roller 7 by an angle equal to the opening angle α of the pair of direction change paths 10, the roller force that applied the load from one direction (1) of the axis of the screw shaft 5 is reversed. Without returning (with the load from the one direction (1) of the axis of the screw shaft 5 can be applied again) to the load roller rolling path 9. The retainer 8 interposed between the rollers can also be returned without being reversed. The The retainer 8 is configured so that the axis of the roller rolling along the annular load roller rolling path is moved toward the center line of the screw shaft as viewed from the axial direction of the screw shaft 5 (this causes the roller to tilt from a predetermined axis). Phenomenon, so-called roller skew can be prevented), and some are formed in a sector shape. If the fan-shaped retainer is reversed, the width on the outer peripheral side of the retainer must be increased, but the width on the inner peripheral side is increased. By rotating the posture of the roller 7 by an angle equal to the opening angle OC of the pair of direction change paths, the roller and the retainer can be prevented from being reversed.

FIG. 18 shows a detailed view of the retainer 8 used in the present embodiment. The retainer 8 maintains the posture of the roller so that the axis of the adjacent roller maintains a right angle. Unlike the fan-shaped retainer described above, this retainer is flat and has a thickness that does not change between the inner peripheral side and the outer peripheral side of the annular load roller rolling path 9.

[0047] Below, the roller screw of this embodiment is superior to the return pipe type roller screw!

[0048] First, even if the lead is large, the roller return path 11 and the direction changing path 10 can be designed without interfering with the roller rolling groove 6a of the nut 6, so that a structure suitable for a large lead is achieved. ing.

[0049] In the return pipe method, the return pipe is attached to the side surface of the nut, so that the size of the nut tends to increase. In the roller screw of this embodiment, the roller return passage 11 is formed inside the nut 6, so that the nut 6 can be made compact. Also, the total length of the nut 6 can be shortened by increasing the number of screws.

[0050] The circulating part is divided into the direction changing path constituting member 13 and the roller returning path constituting member 12, and the roller returning path 11 formed in the linear roller returning path constituting member 12 is twisted. Can be easily manufactured, and the mold can be easily formed.

[0051] With the return pipe method, it is difficult to insert a roller into the circulation path, but with the roller screw of this embodiment, the roller screw is raised and the rollers can be sequentially inserted with the outer peripheral side 13b of the direction change path constituting member removed. So, assembly becomes easy.

[0052] This specification is based on Japanese Patent Application No. 2004-260502 filed on Sep. 8, 2004. All this content should be included here.

Claims

The scope of the claims

[1] A screw shaft having a spiral roller rolling groove formed on the outer peripheral surface, and a nut having a spiral roller rolling groove facing the roller rolling groove of the screw shaft on the inner peripheral surface When,

A roller screw comprising: a plurality of rollers arranged in a load roller rolling path between the roller rolling groove of the screw shaft and the roller rolling groove of the nut;

Inside the nut is provided a roller return passage extending linearly in parallel with the nut axis,

A direction change path constituting member in which a direction change path for connecting the load roller rolling path and the roller return path is formed is attached to both end faces in the axial direction of the nut.

2. The roller screw according to claim 1, wherein the roller return path is twisted so that the posture of the roller rotates while the roller moves in the roller return path.

[3] A center line of the pair of direction change paths provided on both end faces of the nut intersects at a predetermined opening angle when viewed from the axial direction of the screw shaft,

The roller screw according to claim 2, wherein the roller return passage rotates the posture of the roller by the predetermined opening angle.

[4] The nut is formed with a through hole extending in the axial direction of the nut,

4. The roller screw according to claim 2, wherein a roller return path constituting member in which the roller return path is formed is inserted into the through hole.

[5] The roller rolling groove of the screw shaft is formed in a V-shaped cross section,

The roller rolling groove of the nut is also formed in a V-shaped cross section,

The plurality of rollers are arranged in a cross in the loaded roller rolling path so that the axes of adjacent rollers are orthogonal to each other when viewed from the traveling direction of the rollers. 4, Roller screw as described in the slip.

[6] The direction change path component is a thin wall that protrudes toward the nut from the end face of the nut to which the direction change path component is attached, and is bent in a curved shape according to the shape of the direction change path. Part is formed,

On the end face of the nut to which the direction change path component is attached, the direction change 52. The roller screw according to claim 1, wherein a relief groove having a shape is formed in the thin portion of the path constituent member.